Support extern-blocks defined within blocks

This adds support for declaring extern blocks within blocks. So this adds
the missing name resolution visitor for the statement context. Then we
extract out a common extern block hir lowering function for both contexts.

The type resolution step needs to be updated to be like the code-generation
step so that we can solve these paths in a query rather than a top down
approach but this is a known issue.

The final step was to support query based compilation to extern functions.

Fixes #976

1 files changed, 14 insertions, 2 deletions

diff --git a/gcc/rust/backend/rust-compile-resolve-path.cc b/gcc/rust/backend/rust-compile-resolve-path.cc
index bd44bf4..ca96a27 100644
--- a/gcc/rust/backend/rust-compile-resolve-path.cc
+++ b/gcc/rust/backend/rust-compile-resolve-path.cc
@@ -23,8 +23,7 @@
 #include "rust-compile-expr.h"
 #include "rust-hir-trait-resolve.h"
 #include "rust-hir-path-probe.h"
-
-#include "print-tree.h"
+#include "rust-compile-extern.h"
 
 namespace Rust {
 namespace Compile {
@@ -172,7 +171,11 @@ HIRCompileBase::query_compile (HirId ref, TyTy::BaseType *lookup,
 {
   HIR::Item *resolved_item
     = ctx->get_mappings ()->lookup_hir_item (mappings.get_crate_num (), ref);
+  HIR::ExternalItem *resolved_extern_item
+    = ctx->get_mappings ()->lookup_hir_extern_item (mappings.get_crate_num (),
+						    ref);
   bool is_hir_item = resolved_item != nullptr;
+  bool is_hir_extern_item = resolved_extern_item != nullptr;
   if (is_hir_item)
     {
       if (!lookup->has_subsititions_defined ())
@@ -182,6 +185,15 @@ HIRCompileBase::query_compile (HirId ref, TyTy::BaseType *lookup,
 	return CompileItem::compile (resolved_item, ctx, lookup, true,
 				     expr_locus);
     }
+  else if (is_hir_extern_item)
+    {
+      if (!lookup->has_subsititions_defined ())
+	return CompileExternItem::compile (resolved_extern_item, ctx, nullptr,
+					   true, expr_locus);
+      else
+	return CompileExternItem::compile (resolved_extern_item, ctx, lookup,
+					   true, expr_locus);
+    }
   else
     {
       HirId parent_impl_id = UNKNOWN_HIRID;